Setting up App loader to use network core in NRF5340

[aksh_diode]

I am trying to use the network core to turn on an LED in NRF5340-DK. I was able to succeed, but I have a few concerns

In the App core, I had an application that does following

1. Configure :  NRF_P0_S->PIN_CNF[pin] to enable access for network core

2. Set SECATTR  in NRF_SPU_S->EXTDOMAIN[0].PERM  to   1

3. Set NRF_RESET_S->NETWORK.FORCEOFF to 0

In the network core, I would turn on an LED by setting the correct pin NRF_P0_S->PIN_CNF[pin]

My concern is why do I need to do steps 2 and 3 in the App core to turn on the LED using the network core. As far as I can understand, step 2 enables a secure attribute set. I am not able to clearly understand why this is required.

My Environment: I am developing a bare metal application( without any SDK , just CMSIS). Using Jlink to flash firmware.

[Einar Thorsrud]

Hi,

Step 3 is absolutely required. The NETWORK.FORCEOFF is 1 (Hold) after reset, which means that the network core is held if foce-off. So in order to start the network core, the application core needs to write 0 to this register. Regardign 2, this sets the secure attribute on the accesses from the network core (which is the external domain in this context). You can refer to the product specifications for details.

PS: The nRF5340 is a quite complex device and unless you are just playing with it or have a lot of time and resources I would recommend thinking twice before starting development of a real product without utilizing the nRF Connect SDK.

[aksh_diode]

Hi Einar,  Thanks for the comment.